IT6601 Mobile Computing 2 mark question and answers · SYED AMMAL ENGINEERING COLLEGE Dr.E.M.Abdullah Campus, Ramanathapuram - 623502 Department of Information Technology IT6601 Mobile

SYED AMMAL ENGINEERING COLLEGE Dr.E.M.Abdullah Campus, Ramanathapuram - 623502

Department of Information Technology

IT6601 Mobile Computing 2 mark question and answers

UNIT-I

1.What is mobile computing?

Mobile computing is a technology that allows transmission of data, via a computer,

without having to be connected to a fixed physical link. 2. What is Mobility?

• A person who moves Between different geographical locations Between different networks Between different communication devices Between different applications

• A device that moves Between different geographical locations Between different networks

2. What are two different kinds of mobility? User Mobility: It refers to a user who has access to the same or similar telecommunication services at different places. Device Portability: many mechanisms in the network and inside the device have to make sure that communication is still possible while the device is moving. 3. Find out the characteristics while device can thus exhibit during communication.

Fixed and Wired

Mobile and Wired

Fixed and Wireless

Mobile and Wireless

4. What are applications of Mobile Computing? Vehicles

Emergencies

Business

Replacement of wired networks

Infotainment

Location dependent services

Mobile and wireless devices

5. What are the obstacles in mobile communications? Interference

Regulations and spectrum

Low Bandwidth

High delays, large delay variation

Lower security, simpler to attack

Shared Medium

Adhoc-networks




6. Give the information’s in SIM? Card type, serial no, list of subscribed services

Personal Identity Number(PIN)

Pin Unlocking Key(PUK)

An Authentication Key(KI)

7. What are the Advantages of wireless LAN? Flexibility

Planning

Design

Robustness

8. Mention some of the disadvantages of WLANS? Quality of service

Proprietary solutions.

Restrictions

Safety and Security

9. Describe about MAC layer in DECT architecture. The medium access control (MAC) layer establishes, maintains and releases channels for

higher layers by activating and deactivating physical channels. MAC multiplexes several logical

channels onto physical channels. Logical channels exist for signaling network control, user data transmission, paging or sending broadcast messages. Additional services offered include

segmentation/reassembly of packets and error control/error correction.

10. What are the basic tasks of the MAC layer? Medium access Fragmentation of user data Encryption

11. What are the basic services provided by the MAC layer? Asynchronous data service (mandatory)

Time-bounded service (optional)

12. What are the techniques used for MAC management? Synchronization

Power management

Roaming

Management information base(MIB) 13. Describe about MAC layer in DECT architecture.

The medium access control (MAC) layer establishes, maintains and releases channels for higher layers by activating and deactivating physical channels. MAC multiplexes several

logical channels onto physical channels. Logical channels exist for signaling network control, user data transmission, paging or sending broadcast messages. Additional services offered

include segmentation/reassembly of packets and error control/error correction.

14. Define hidden terminal. The transmission range of A reaches B but not C. The transmission range of C reaches

B but not A. B reaches A and C. A cannot detect C and vice versa. A starts sending to B, but C does not receive this transmission. C also wants to send something to B and senses the medium. The medium appears to be free, the carrier sense fails. C also starts




sending, causing a collision at B. But A can’t detect this collision at B and continues with its transmission. A is hidden for C and vice versa.

15. What is Mobile Computing and the applications ? Mobile computing is the process of computation on a mobile device. In such computing,

a set of distributed computing systems or service provider servers participate, connect , and

synchronise through mobile communication protocols.

APPLICATIONS:

i) Mobile computing offers mobility with computer power.

ii) It provides decentralized computations on diversified devices, systems, and networks, which are mobile, synchronized , and interconnected via mobile communication

standards and protocols. iii) Mobile computing facilitates a large number of applications on a single device.

16.Limitations of Mobile Computing?

i)Resource constraints.

ii)Interface

iii)Bandwidth iv)Dynamic changes in communication environment. v)Network issues. vi)Interoperability issues.

vii)Security Constraints.

17.Give the difference between the network 1G,2G,2.5G,3G mobile communication?

1G - Voice-only communication.

2G – Communicate voice as well as data signals.

2.5G – Enhancements of the second generation and sport data rates up to 100 kpbs. 3G – Mobile devices communicate at even higher data rates and support voice, data , and multimedia streams. High data rates in 3G devices enable transfer of video clips and faster multimedia communication.

18. Difference between Hidden and Exposed Terminal, Near and Far Terminals. Hidden and Exposed Terminals

A B C

Let us consider three mobile phones A,B and C




Transmission range of A reaches B but not C, C reaches B, but not A

B reaches both A and C

A starts sending to B but

C does not receive this transmission ,C also wants to send something to

Band senses the medium For C medium appears to be free and carrier sense fails, then C sends but it collides at B. Now A cannot detect collision at B and A also transmits, now A is hidden for C and vice versa. A is

hidden terminal and these hidden terminals may cause collision and unnecessary delay.

Let us consider another scenario where ‘B’ sends something to ‘A’ and ‘C’ wants to transmit data to some other mobile phones outside the interference ranges pf A and B. C senses the carrier and detects that the carrier is busy ; C postpones its transmission until it detects the medium is free ; but as A is outside the interference range of C, waiting is not necessary. I.e.

collision at B does not matter because the collision is too weak to propagate to A.

Near and Far Terminals

Let us consider that A and B both sending with the same transmission power.

When the signal strength decreases proportionally to the square of the distance B’s signal drowns out A’s signal .As a result ‘C’ cannot receive ‘A’s transmission.

Now think of ‘C’ as being an arbiter for sending rights. In this case terminal B would already

drown out terminal A on the physical layer.

‘C’ in return would have no chance of applying a fair scheme as it would only hear B.

The near/far effect is a severe problem of the wirelessnetwork using the CDM.All signals

should arrive at the receiver with more or less the same strength.

Otherwise a person standin

g closer to somebody could always loud than a person farther away. Even if the sender

were separated by code , the closest one would simply drown out the others.




19. What is MAC? Message authentication codes (MAC) are also used to authenticate messages during

transmission. MAC of a message is created using a cryptographic MAC function which is similar to

the hash function but has different security requirements.

20.Define Mobile Binding? A binding created for providing mobility to a mobile node after registration at a

foreign network.

21.Agent-based Computing An agent is any program that acts on behalf of a (human) user. A software mobile agent is a

process capable of migrating from one computer node to another. 22.Ubiquitous computing

Ubiquitous computing enhances computer use by making many computers available throughout the physical environment, while making them effectively invisible to users.

23.Client-Server Computing

An architecture in which the client is the requesting machine and the server is the supplying machine. The client contains the user interface and may perform some or all of the application processing. 24. What do you mean by Digital Signature?

Digital signatures are used to enable verification of the records. A DSA (Digital Structure

Algorithm) is used to sign a record before transmitting. It provides for a variable key length of

maximum 512 0r 1024 bits. The DSS(Digital Signature Standard) is based on the DSA.Signatures

enable identification of the sender identify the orgin of the message, and check message integrity.

25. Define the term wireless?

Wireless telecommunications refers to the transfer of information between two or more

points that are not physically connected. Distances can be short, such as a few metres for television

remote control, or as far as thousands or even millions of kilometers for deep-space radio

communications. It encompasses various types of fixed, mobile, and portable applications, including

two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking.

26. What are the different types of mobile Middleware? 1.Adaptation 2.Agent

27.What are the logical channels in GSM? • Traffic channel(TCH)

• Control channel(CCH) 28. Define the term wireless?

Wireless telecommunications refers to the transfer of information between two or more

points that are not physically connected. Distances can be short, such as a few metres for television

remote control, or as far as thousands or even millions of kilometers for deep-space radio

communications. It encompasses various types of fixed, mobile, and portable applications, including

two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking.




29. Define GPRS? General Packet Radio Service (GPRS) is a packet oriented service for mobile devices data

communication which utilizes the unused channels in TDMA mode in a GSM network and also

sends and receives packet of data through the internet.

30. What is Communication? Communication is a two-way transmission and reception and reception of data streams.

Transmissions are of two types, Guided Transmission Unguided Transmission

31. Explain difference between wired and wireless networks

Wired Vs. Wireless Networks

Wired Networks Mobile Networks

- high bandwidth - low bandwidth - low bandwidth variability - high bandwidth variability

- can listen on wire - hidden terminal problem

- high power machines - low power machines

- high resource machines - low resource machines

- need physical access(security) - need proximity

- low delay - higher delay

32. Types of Wireless Devices Laptops Palmtops PDAs Cell phones

Pagers

Sensors

33. Why Mobile Computing?

Enable anywhere/anytime connectivity Bring computer communications to areas without pre existing infrastructure Enable mobility Enable new applications

An exciting new research area 34.what are the New Forms of Computing available?.

Wireless Computing Nomadic Computing Mobile Computing

Ubiquitous Computing

Pervasive Computing Invisible Computing




35.Mobile Communication Networks: Examples

GSM (Global System for Mobile Communications): worldwide standard for digital, cellular Mobile Radio Networks

UMTS (Universal Mobile Telecommunications System): European Standard for future digital Mobile Radio Networks

AMPS (Advanced Mobile Phone System): analog Mobile Radio Networks in USA DECT (Digital Enhanced Cordless Telecommunications): European standard for cordless phones

TETRA (Terrestrial Trunked Radio): European standard for circuit switched radio networks ERMES (European Radio Message System): European standard for radio paging systems (Pager) 802.11: International standard for Wireless Local Networks Bluetooth: wireless networking in close/local area Inmarsat: geostationary satellite systems Teledesic: planned satellite system on a non-geostationary orbit

36.Components of a wireless communication system Transmitter, receiver, filter, antenna, amplifier, mixers

37.Wireless Networking Standards (Table1.1) ITU, IEEE and ISO IEEE 802.11 standards (a,bc,d,e,f…u)

38.Classification of wireless MAC protocols

39.What are the disadvantages of small cells?

a) Infrastructure b) Handover c) Frequency 40. What are the benefits of reservation schemes?

a) Increased no other station is allowed to transit during this slot b) Avoidance of congestion.

c) Waiting time in clearly known. 3. Differentiate between free space loss and path loss. Free space loss Path loss




41. Define hidden terminal. The transmission range of A reaches B but not C. The transmission range of C reaches B but not A. B reaches A and C. A cannot detect C and vice versa. A starts sending to B, but C does not receive this transmission. C also wants to send something to B and senses the medium. The medium appears to be free, the carrier sense fails. C also starts sending, causing a collision at B. But A can’t detect this collision at B and continues with its transmission. A is hidden for C and vice versa.

42.Mobile Computing - Characteristics –Mobile devices

•Laptops

•Palmtops •Smart cell phones

–Requirements •Data access:

–Anywhere –Anytime

•Nomadic users

–Constraints •Limited ressources •Variable connectivty:

–Performance

–Reliability

43. What are the different types of modulation ?

The Modulation types are: i).Amplitude Modulation. ii).Frequency Modulation. iii).Phase Modulation. 44. What are the multiplexing techniques ?

The Multiplexing techniques are: i)Space division multiplexing. ii)Time division multiplexing. iii)Frequency division multiplexing. iv)Code division multiplexing.

45. Define Space Division Multiplexing Access? Space division multiple access (SDMA) means division of the available space so that

multiple sources can access the medium at the same time. SDMA is the technique in which a

wireless transmitter transmits the modulated signals and accesses a space slot and another

transmitter accesses another space slot such that signals from both can propagate in two separate

spaces in the medium without affecting each other.

46. Define Code division multiplexing Access? CDMA(Code Division Multiple Access) is an access method in which multiple users are

allotted different codes (sequence of symbols) to access the same channel (set of frequencies)

47. Define Time division multiplexing Access? Time division multiplexing (TDMA) is an access method in which multiple users, data

services, or sources are allotted different time-slices to access the same channel. The available

time-slice is divided among multiple modulated-signal sources. These sources use the same

medium, the same set of frequencies, and the same channel for transmission of data.




48. Define Frequency division multiplexing Access? Frequency division multiple access (FDMA) is an access method in which entails

assignments of different frequency-slices to different users for accessing the same carrier.

49. Difference between Circuit Switching and Packet Switching?

CIRCUIT SWITCHING : Circuit switching is a method of data transmission in which a circuit (Communication

channel or path) once established, continues to be used till the transmission is complete.

PACKET SWITCHING : Packet switching is a means of establishing connection and transmitting data in which the

message consists of packets containing the data frames. A packet is a formatted series of data,

which follows a distinct path directed by a router from among a number of paths, available at that

instant. 50.What is CSMA

The capacity of ALOHA or slotted ALOHA is limited by the large vulnerability period of a packet.

•By listening before transmitting, stations try to reduce the vulnerability period to one propagation delay.

•This is the basis of CSMA (Kleinrock and Tobagi, UCLA, 1975). The capacity of ALOHA or slotted ALOHA is limited by the large vulnerability period of a

packet. •By listening before transmitting, stations try to reduce the vulnerability period to

one propagation delay. •This is the basis of CSMA (Kleinrock and Tobagi, UCLA, 1975). Station that wants to transmit first listens to check if another transmission is in

progress (carrier sense). •If medium is in use, station waits; else, it transmits. •Collisions can still occur. •Transmitter waits for ACK; if no ACKs, retransmits.

51.What is the aim of ubiquitous computing? (AUT-NOV/DEC 2012)

• The aim of ubiquitous computing is to design computing infrastructures in such a

manner that they integrate seamlessly with the environment and become almost invisible. • Present Everywhere Bringing mobile, wireless and sensor Ubiquitous computing

(ubicomp) integrates computation into the environment, rather than having computers

which are distinct objects 52. What are the characteristics of mobile computing devices?

• Adaptation Data dissemination and Management • Heterogeneity Interoperability Context awareness

53. What are the key constraints of mobile computing? • unpredictable variation in network quality • lowered trust and robustness of mobile elements

SYED AMMAL ENGINEERING COLLEGE

Dr.E.M.Abdullah Campus, Ramanathapuram - 623502



54. N-Tier Client-Server Framework and Tools

N-Tier -Any Number of Tiers – No Limits

• 3-Tier

Client (User Agent)

Application Server

Database

55. Define FDMA?

Frequency division multiple access (FDMA) This comprises all algorithms allocating frequencies to transmission channels

according to the frequency division multiplexing (FDM). Frequency can be fixed or dynamic

56. Define CDMA?

An access method in which multiple carriers, channels, or sources are allotted different

codes (Sequences and Symbols) to access the same channel (set of frequencies at the same time in

same space).

57. What is ALOHA?

The ALOHAnet used a new method of medium access (ALOHA random access) and

experimental UHF frequencies for its operation, since frequency assignments for communications

to and from a computer were not available for commercial applications in the 1970s. But even

before such frequencies were assigned there were two other media available for the application of

an ALOHA channel – cables and satellites. In the 1970s ALOHA random access was employed in

the widely used Ethernet cable based network and then in the Marisat (now Inmarsat) satellite

network.

In the early 1980s frequencies for mobile networks became available, and in 1985 frequencies

suitable for what became known as Wi-Fi were allocated in the US. These regulatory developments

made it possible to use the ALOHA random access techniques in both Wi-Fi and in mobile

telephone networks.




UNIT-II

1. What are the requirements of mobile IP? Compatibility

Transparency

Scalability and efficiency

Security

2. Mention the different entities in a mobile IP. Mobile Node

Correspondent Node

Home Network

Foreign Network

Foreign Agent

Home Agent

Care-Of address

Foreign agent COA

Co-located COA

3. Define Mobile node:

A mobile node is an end-system or router that can change its point of attachment to the Internet using mobile IP. The MN keeps its IP address and can continuously with any other system in the Internet as long as link layer connectivity is given. 4. Explain Cellular IP.

Cellular IP provides local handovers without renewed registration by installing a single cellular IP gateway for each domain, which acts to the outside world as a foreign agent. 5. What do you mean by mobility binding?

The Mobile Node sends its registration request to the Home Agent. The HA now sets up a mobility binding containing the mobile node’s home IP address and the current COA. 6. Define COA.

The COA (care of address) defines the current location of the MN from an IP point of view. All IP packets sent to the MN are delivered to the COA, not directly to the IP address of the MN.

Packet delivery toward the MN is done using the tunnel. DHCP is a good candidate for supporting the acquisition of Care Of Addresses. 7. Define a tunnel.

A tunnel establishes a virtual pipe for data packets between a tunnel entry and a tunnel endpoint. Packets entering a tunnel are forwarded inside the tunnel and leave the tunnel unchanged. 8. What is encapsulation?

Encapsulation is the mechanism of taking a packet consisting of packet header and data putting it into the data part of a new packet.




9. What is decapsulation?

The reverse operation, taking a packet out of the data part of another packet, is called decapsulation.

10. What is MOT? Give its primary goal.

DAB faces a broad range of different receiver capabilities. So to solve this problem it defines

a common standard for data transmission, the multi-media object transfer (MOT) protocol. The

primary goal of MOT is the support of data formats used in other multimedia systems.

11. What is SUMR? An important register in satellite networks is the satellite user mapping register (SUMR).

This stores the current position of satellites and a mapping of each user to the current satellite through which communication with a user is possible. 12. Give the two basic reasons for a handover in GSM.

The mobile station moves out of the range of a BTS or a certain antenna of a BTS. The received signal level decreases continuously until it falls below the minimal requirements for

communication. The error rate may grow due to interference. All these effects may diminish the quality of the radio link. The wired infrastructure may decide that the traffic in one cell is too high and shift some MS to other cells with a lower load. Handover may be due to load balancing.

13. Give the security services offered by GSM. Access control and authentication Confidentiality Anonymity

14. What is the primary goal of GSM? The primary goal of GSM was to provide a mobile phone system that allows users to roam

throughout Europe and provides voice services compatible to ISDN and other PSTN systems. 15. Differentiate GSM and DECT.

GSM DECT

1. Global systems for mobile communications 2. Digital enhanced cordless elecommunications

3. Range is up to 70km.

4. Range is limited to about 300m. 16. What are the two new network elements in GPRS architecture?

Gateway GPRS support node (GGSN): It is the inter-working unit between the GPRS network and external packet data networks (PDN). Serving GPRS support node (SGSN): It supports the MS.

17. Describe about MAC layer in DECT architecture. The medium access control (MAC) layer establishes, maintains and releases channels for

higher layers by activating and deactivating physical channels. MAC multiplexes several logical

channels onto physical channels. Logical channels exist for signaling network control, user data transmission, paging or sending broadcast messages. Additional services offered include

segmentation/reassembly of packets and error control/error correction.




18. Give the full form for the following:

a) CKSN b) EIR c) DTMF d) MOC

a) CKSN- Ciphering key sequence number b) EIR- Equipment Identity Register c) DTMF- Dual Tone multiple frequency d) MOC- Mobile originated call

19. Define Snooping TCP? A protocol in which an agent buffers the packets from the fixed connection layer for

transmission to the mobile node on a wireless transceiver; the agent also buffers the packets on the

wireless transceiver from the node for transmitting to a layer at the fixed line. The agent snoops at the transmission and reception in place of acknowledgement-or-timeout-based TCP method in the

mobile part of the network.

20. Define Mobile TCP? A method of splitting the TCP layer into two TCP sub-layers using a mechanism that

reduces window size to zero. The split is asymmetric; The window is set to zero to prevent the

transmission from the TCP transport layer at the mobile node (MN) or at the fixed node when

disconnection is noticed. The window opens again on getting the packet, there is no slow start by

the base transceiver and it is presumed that packet loss is due to disconnection and not due to

congestion or interference. 21. Explain the concept “Fast Retransmit/ Fast Recovery Transmission”?

A method in which there are four or more phases of fast retransmit and fast recovery –first phase as slow start and beginning (exponential), then fast retransmit/recovery phase 1 (FRR1) on

three duplicate acknowledgements, fast retransmit/fast recovery phase 2 (FRR2), and wait (Constant time out and window size).

22. Define T-TCP? A protocol which is efficient and is used in situations where short messafes are to be sent

in sequence and a packet is delivered after the SYN and SYN_ACK packet exchanges and the connection closes after the packet exchanges of FIN, FIN_ACK, and CLOSING. 23. Define ISR?

Interrupt Service Routine(ISR): A program unit (function, method, or subroutine) which runs when a hardware or software

event occurs and running of which can be masked and can be prioritized by assigning a priority.

24.Define IST? Interrupt Service Thread(IST):

A special type of ISR or ISR unit (function, method , or subroutine) which initiates and runs on an event and which can be prioritized by assigning a priority. 25.Features of TCP?

The main features of TCP are:

1) Transmission as data Streams

2) Buffering and retransmission 3)Session-start, data transfer, and session-finish fully acknowledged end to end. 4)In-order delivery 5)Congestion Control and avoidance




26. What is explicit notification? A method of congestion control by explicit notification of congestion, for example, when a

base transceiver at the receiver end is not able to transmit a packet to the mobile node then it sends

an ESBN (explicit bad state notification) to the sender (on fixed line ) at the other end. 27. What is selective retransmission?

A method in which there is an additional acknowledgement, known as selective

acknowledgement; a timeout is set at transmitting end for receiving SACKs. Only the lost packet

corresponding ta a SACK needs to be retransmitted. 28. Methods of Congestion Control.

The methods of congestion control:

1) Slow start and congestion avoidance 2) Fast recovery after packet loss 3) Fast retransmit and fast recovery 4) Selective acknowledgement 5) Explicit congestion notification

29. TCP header. A header used in the TCP protocol; it consists of fields in five 32-bit

words followed by words for the option fields and padding.

30. Describe the three subsystems of GSM. Radio subsystem (RSS): It comprises all radio specific entities i.e. the mobile stations (MS)

and the base station subsystem (BSS). Networking and switching subsystem (NSS): The heart of the GSM system is formed by the NSS. This connects the wireless network with standard public networks. Operating subsystem (OSS): It monitors and controls all other network entities.

31. What are the applications of satellites? Weather forecasting Radio and TV broadcast satellites Military satellites Satellites for navigation

32.Application Layer n protocols File Transfer Protocol (FTP)

Trivial File Transfer Protocol (TFTP) Network File System (NFS)

Simple Mail Transfer Protocol (SMTP)

Terminal emulation protocol (telnet)

Remote login application (rlogin)

Simple Network Management Protocol (SNMP)

Domain Name System (DNS)

Hypertext Transfer Protocol (HTTP) 33.What are Advantage and Disadvantage of MobileTCP?

Advantages: i. M-TCP maintains the TCP end-to-end semantice. The SH does not send any

ACK itself but forwards the ACKs from the MH. ii.If the MH is disconnected, M_TCP avoids useless retransmissions, slow starts or breaking connections by simply shrinking the sender’s

window to 0; iii. Since M-TCP does not buffer data in the SH as I-TCP does, it is not necessary to

forward buffers to a new SH. Lost packets will be automatically retransmitted to the new SH.




Disvantages: i. As the SH does not act as proxy as in I-TCP, packet loss on the wireless link due to bit errors is propagated to the sender. M-TCP assumes low bit error rates, which is not

always a valid assumption. ii. A modified TCP on the wireless link not only requires modification to the MH protocol software but also new network elements like the bandwidth

manager 34. What is mobile routing?

Even if the location of a terminal is known to the system, it still has to route the traffic

through the network to the access point currently responsible for the wireless terminal. Each

time a user moves to a new access point, the system must reroute traffic. This is known as

mobile routing. 35. What are the functions which support service and connection control?

Access point control function

>Call control and connection control

function >Network security agent

>Service control function >Mobility management function 36.What are the examples for service scenarios identified in WATM ?

>Office environments

>Universities, schools, training,

centres >Industry >Hospitals

>Home >Networked vehicles

37. What is slow start?

TCP’s reaction to a missing acknowledgement is necessary to get rid of congestion quickly. The behavior TCP shows after the detection of congestion is called slow start. 38. What is the use of congestion threshold?

The exponential growth of the congestion window in the slow start mechanism is

dangerous as it doubles the congestion window at each step. So a congestion threshold is set at

which the exponential growth stops. 39. What led to the development of Indirect TCP? TCP performs poorly together with wireless links TCP within the fixed network cannot be changed. ,This led to the development of I-TCP

which segments a TCP connection into a fixed part and a wireless part. 40. What is the goal of M-TCP?

The goal of M-TCP is to prevent the sender window from shrinking if bit

errors or disconnection but not congestion cause current problems. It wants

• To provide overall throughput • To lower the delay • To maintain end-to-end semantics of TCP • To provide a more efficient handover.

41. What do you mean by persistent mode? Persistent mode is the state of the sender will not change no matter how long thereceiver is

disconnected. This means that the sender will not try to retransmit the data.




42. What are the characteristics of 2.5G/3.5G wireless networks? Data rates

Latency

Jitter

Packet loss

43. What are the configuration parameters to adapt TCP to wireless environments? Large Windows

Limited Transmit

Large MTU

Selective Acknowledgement

Explicit Congestion

Notification Timestamp No header compression

44.Requirements to Mobile IP Transparency mobile end-systems keep their IP address

continuation of communication after interruption of link

possible point of connection to the fixed network can be

changed Compatibility

support of the same layer 2 protocols as IP

no changes to current end-systems and routers required

mobile end-systems can communicate with fixed

systems Security

authentication of all registration

messages Efficiency and scalability

only little additional messages to the mobile system required (connection typically via a

low bandwidth radio link) world-wide support of a large number of mobile systems in the whole Internet 45.Mobile IP Terminology Mobile Node (MN)

system (node) that can change the point of connection to the network without changing its IP address

Home Agent (HA) system in the home network of the MN, typically a router registers the location of the MN, tunnels IP datagrams to the COA Foreign Agent (FA)

system in the current foreign network of the MN, typically a router forwards the tunneled datagrams to the MN, typically also the default router for the

MN Care-of Address (COA) address of the current tunnel end-point for the MN (at FA or MN) actual location of the MN from an IP point of view can be chosen, e.g., via DHCP

Correspondent Node (CN)

communication partner




45.What Mobile IP Mobile IP solves the following problems:

if a node moves without changing its IP address it will be unable to receive its packets, if a node changes its IP address it will have to terminate and restart its ongoing connections everytime it moves to a new network area (new network prefix). Mobile IP is a routing protocol with a very specific purpose.

Mobile IP is a network layer solution to node mobility in the Internet. Mobile IP is not a complete solution to mobility, changes to the transport protocols need to be made for a better solution (i.e., the transport layers are unaware of the mobile node’s point of attachment and it might be useful if, e.g., TCP knew that a wireless link was being used!).




UNIT III

MOBILE TELECOMMUNICATION SYSTEM

1. Define GSM? The global system for mobile communication (GSM) was developed by Groupe Speciale

Mobile(GSM) which was founded in Europe in 1992. The Gsm is a standard for mobile

telecommunication through a cellular network at data rates if upto 14.4 kbps. Now a days it consist

of a set of standards and protocols for mobile telecommunication. 2. Define GPRS?

General Packet Radio Service (GPRS) is a packet oriented service for mobile devices data

communication which utilizes the unused channels in TDMA mode in a GSM network and also

sends and receives packet of data through the internet.

3. What are subsystems in GSM system?

Radio subsystem (RSS) Network & Switching subsystem (NSS) Operation subsystem (OSS)

4. What are the control channel groups in GSM? The control channel groups in GSM are:

Broadcast control channel (BCCH) Common control channel (CCCH)

Dedicated control channel (DCCH)

5. What are the four types of handover available in GSM? Intra cell Handover Inter cell Intra BSC Handover Inter BSC Intra MSC handover Inter MSC Handover

6. What is the frequency range of uplink and downlink in GSM network? The frequency range of uplink in GSM network is 890-960 MHz The frequency range of downlink in GSM network is 935-960 MHz

7. What are the security services offered by GSM? The security services offered by GSM are: Access control and authentication. Confidentiality. Anonymity.

8. What are the reasons for delays in GSM for packet data traffic? Collisions only are possible in GSM with a connection establishment. A slotted ALOHA

mechanism is used to get access to the control channel by which the base station is told about the

connection establishment attempt. After connection establishment, a designated channel is installed for the transmission.




9. What is meant by beacon? A beacon contains a timestamp and other management information used for power management and roaming. e.g., identification of the base station subsystem (BSS)

10 . List out the numbers needed to locate an MS and to address the MS. The numbers needed to locate an MS and to address the MS are: Mobile station international ISDN number (MSISDN)

International mobile subscriber identity (IMSI) Temporary mobile subscriber identity (TMSI)

Mobile station roaming number (MSRN)

11 . What is meant by GPRS? The General Packet Radio Service provides packet mode transfer for applications that exhibit

traffic patterns such as frequent transmission of small volumes. 12. What is meant by GGSN?

GGSN is Gateway GPRS Support Node. It is the inter-working unit between the GPRS network and external packet data networks. The GGSN is connected to external networks via the Gi interface and transfers packets to the SGSN via an IPbased GPRS backbone network. 13. What is meant by SGSN? SGSN is Serving GPRS Support Node. It supports the MS via the Gb interface. The GSN is

connected to a BSC via frame relay. 14. What is meant by BSSGP? BSSGP is Base Station Subsystem GPRS Protocol. It is used to convey routing and QoS- related

information between the BSS and SGSN.BSSGP does not perform error correction and works on top of a frame relay network.

15.Expand GSM, GPRS and UMTS.

Global System for Mobile Communication (GSM)

General Packet Radio Service (GPRS)

Universal Mobiie Telecommunication System (UMTS)

16. Mention the types of Interface in GSM system and its use.

• A interface

Makes the connection between the RSS and the NSS

Based on circuit-switched PCM-30 systems (2.048 Mbit/s), carrying up to

30 64 kbit/s connections

• 0 interface

Makes the connection between the RSS and the OSS Uses the Signalling System No.7 (SS7) based on X.25 carrying management

data to/from the RSS

U interface

o Makes the connection between the BTS and MS o Contains all the mechanisms necessary for wireless transmission




Ab. interface

IS Makes the connection between the BTS.and BSC Consists of 16 or 64 kbitls connections

17.What is RSS?

RSS stands for Radio subsystem (RSS)

RSS comprises all radio specific entities

18.Name the entities ofRSS.

Base Station Subsystem (BSS)

Base Transceiver Station (BTS)

Base Station Controller (BSC) Mobile Station (MS)

19.Mention the advantages of GSM. o Communication

Total mobility

Worldwide connectivity

High capacity

High transmission quality' Security functions

20.What does SIM card contain? • a personal identity number (PIN) • a PIN unblocking key (PUK) • an authentication key Ki

• the international mobile subscriber identity (IMSI) 21. Mention the disadvantages of GSM.

No end-to-end encryption of user data Reduced concentration while moving

Electromagnetic radiation

High complexity of system

Several incompatibilities within the GSM standards

Card-type Serial number

A list of subscribed services

22.Mention the use of SS7. • Used for handling all signaling needed for

connection setup,

connection release and

connection release and handover of connections to other MSCs




UNIT IV

IVMOBILE AD-HOC NETWORKS

1.Define MANET. • MANET - Mobile Adhoc NETworks . Continuously self-configuring, infrastructure-less network of mobile devices connected

without wires

2. List the advantages of MANET.

Independence from central network administration

• Self-configuring, nodes are also routers • Self-healing through continuous re-configuration

• Scalable-accommodates the addition of more nodes

• Flexible-similar to being able to access 'the Internet from many different locations

• Ease of deployment

• Speed of deployment

• Decreased dependence on infrastructure

. Reduced administrative cost

• Supports anytime and anywhere computing

3. What are the limitations of MANET?

•Each node must have full performance

•Throughput is affected by system loading

•Reliability requires a sufficient number of available nodes

•Large networks can have excessive latency (time delay), which affects some applications

•Limited wireless range •Hidden terminals •Packet losses due to transmission errors •Routes changes

•Devices heterogeneity •Battery power

constraints •Link changes are happening quite often •Routing loop

may exist




4. Difference between cellular and Ad-Hoc Networks

CELLULAR Ad-Hoc NETWORKS

Infrastructure Networks Infrastructureless Networks

Fixed, pre-located cell sites and base

No base station, and rapid deployment stations

Static backbone network topology Highly dynamic network topologies

Relatively caring environment and Hostile environment and irregular

stable connectivity connectivity

Detailed planning before base station Ad-Hoc network automatically forms

can be installed and adapts to changes

High setup costs Cost-effective

Large setup time Less setup time

5. What are the functions of each node in MANET? • Forward the packet to the next hop

Before forwarding, Sender has to ensure that:

. the packet moves towards its destination

b. the number of hops(path length) to destination is minimum

c. Delay is minimized

d. Packet loss is mimimum through the path

. Path does not have a loop 6. Comparison of Link state and Distance vector.

Routing Building Router can Conver- Event driven Use of

protocol Topological Independently gence routing up- LSP

map determine the dates

shortest path (instead of

to every periodic

network updates)

Link State Yes Yes Fast Generally Yes Yes

Distance No No Slow Generally No No

Vector




7. List the Types of Communications. • Unicast

o Message is sent to a single destination node

Multicast

o Message is sent to a selected subset of network nodes

Broadcast

Broadcasting is a special case of multicasting

Message is sent to all the nodes in the network

8. Define Proactive (table-driven) protocols. Also known as table-driven routing protocols Each node in the routing table maintains information about routes to every

other node in the network

o Tables are updates frequently due to

• Changes in network topology

• Node Movements N odes shutting down

o Nodes can determine the best route to adestination

Generates a large number of control messages to keep. the routing tables up-to-date

o Generates overhead which consumes large part of available bandwidth

9. Define Reactive protocols. Also called as On-demand routing protocol Nodes do not maintain up-to-date routing information o New routes are discovered only when required Uses flooding technique to determine the routeO Flooding technique is used when the node does not have routing knowledge

10. Compare MANET Vs VANET

MANET VANET

MANET - Mobile Adhoc NETwork VANET- Vehicular Adhoc NETworks

Nodes moves r£t?domly Nodes moves regularly

Mobility is low Mobility is high

Reliability is medium Reliability is high

Node lifetime depends on power source N ode lifetime depends on vehicle life

time

Network topology is sluggish and slow Network topology is frequent and fast




UNIT V

VMOBILE PLATFORMS AND APPLICATIONS

1.Define Operating System.

Interface between hardware and user

Manages hardware and software resources of the system

Provides set of services to application programs

2.Name the features of Operating System. • Multitasking

• Scheduling

• Memory Allocation

• File System Interface

• Keypad Interface

• I/O Interface

• Protection and Security

• Multimedia features 3. How is the operating system structured?

Kernel Layer

Shell Layer

4. Give the types of Operating System.

Monolithic Kernel

Micro kernel

5. Specify the motivation of Monolithic Kernel OS design.

Kernel contains the entire OS operations except shell

code Motivation

o OS services can run more securely and efficiently in supervisor mode

6. Mention the examples of Monolithic Kernel OS design.

Windows

Unix

7. List the Advantages of Monolithic Kernel OS design.

Provides good performance

Always runs in supervisor mode

More efficient and secure

8. List the disadvantages of Monolithic Kernel OS design. o Makes kernel

• Massive

Non-modular

Hard to tailor

• Maintain

Extend

Configure




9. List the disadvantages of Microkernel OS design. • Flexible • Modular

Easier to port

Easy to extend and implement 10. List the disadvantages of Microkernel OS design,

Difficult to debug compared to application programs

Bog in the kernel crashes the system and the debugger

Non- reliable11. What is Mobile OS?

Facilitate third party development of application software Allow manufacturers of different brands of mobile devices to build their

choice set of functionalities for the users12. Give some examples of Mobile OS.

• Windows Mobile

• Palm OS

• Symbian OS

• iOS

• Android

• Blackberry

13. What are the five parts in Android architecture or Android software stack?

Application Layer

Application Framework

Android Runtime

Native libraries (Middleware)

Linux kernel14. What are the Key services provided in Application Framework?

• Activity Manager

• Content Providers

• Resource Manager

• Notifications Manager

• View System

15. List the Native libraries in Android architecture. WebKit - web browser engine OpenGL

FreeType - font support

• . SQLite - SQL database

Media - playing and recording audio and video formats MP3

MPEG-4 , • C runtime library (libc) etc




16.Mention the responsibilities of Linux Kernel.

• Device drivers • Power management • Networking Functionalities . • Memory management • Device management • Resource access

17. What is M-Commerce? • M-Commerce stands for Mobile Commerce • Buying and selling of goods and services through mobile handheld devices

18. Compare B2C and B2B.

B2C B2B

B2C stands for Business- to-Consumer B2B stands for Business- to- Business

Form of commerce in which products or Form of commerce in which products or

services are sold by a business firm to a services are sold from a company to its

consumer dealers

17. What is the function of transport layer in WAP? The transport layer offers a bearer independent, consistent datagram-oriented service to the higher

layers of the WAP architecture. Communication is done transparently over one of the available bearer services. 18. What is the use of WCMP?

The wireless control message protocol provides error handling mechanisms for WDP. WCMP is

used for diagnostic and informational purposes. It is used by WDP nodes and gateways to report errors.

19. What are the advantages of WTP? WTP offers several advantages to higher layers, including an improved reliability over datagram

services, improved efficiency over connection-oriented services and support for transaction-oriented services such as web browsing. 20. How is reliability achieved in WTP?

WTP achieves reliability using duplicate removal, retransmission, acknowledgements and unique transaction identifiers. 21. What are the service primitives offered by WTP?

The three service primitives offered by WTP are o TR-Invoke to initiate a new transaction o TR-Result to send back the result of a previously initiated transaction o TR-Abort to abort an existing transaction.

22. What are the features offered by WSP? WSP offers certain features for content exchange between cooperating clients and servers: Session management Capability negotiation

Content encoding.




23. What are the features offered by WSP/B? In addition to the general features of WSP, WSP/B offers the following features adapted to web

browsing: HTTP/1.1 functionality

Exchange of session headers

Push and pull data transfer

Asynchronous requests

24. What is meant by WML? The wireless markup language(WML) is based on the standard HTML known from the www and

on HDML. WML is specified as an XML document type. WML follows a deck and card metaphor. 25. What are the capabilities of WMLScript?

WMLScript offer several capabilities:

Validity check of user input Access to device facilities Local user interaction Extension to the device software

26. Define WTA Wireless telephony application (WTA) is a collection of telephony specific extensions for call

and feature control mechanisms, merging data networks and voice networks. 27. What do you mean by MMS?

The multimedia messaging service (MMS) transfers asynchronous multi-media content. MMS supports different media types such as JPEG, GIF, text and AMR coded audio. There is no fixed upper bound for the message size. Depending on the network operator and device capabilities typical sizes are 30-100 Kbytes. 29 What are the two functions of transport layer in the internet ?

1) Checksumming over user data. 2) Multiplexing/Demultiplexing from /to applications.

30. Distinguish TCP& UDP ?

TCP UDP

1) Connection oriented protocol Connection less protocol

2) TCP is network friendly UDP is not network friendly

3) TCP guarantees in-order delivery or

reliable data transmission using

Retransmission techniques. Does not pull back in case of congestion to send packets in to an already congested network.

16 MARKS – KEYPOINTS

1.Explain in detail about Signal Propagation. Path loss of radio signals Ground wave Sky wave

Line-of-sight Additional Signal propagation effects

Blocking (or) Shadowing, Reflection, Refraction, Scattering, Diffraction

Multi-path propagation Delay Spread

Intersymbol Interference Short-term fading, long-term fading Doppler Shift




2. Write a brief note about multiplexing.

Space division multiplexing Guard space disadvantages Frequency division multiplexing Adjacent Channel Interference disadvantages Time division multiplexing Guard spaces Co-channel Interference

Advantages, disadvantages Code division multiplexing

Guard spaces- orthogonal codes Advantages, disadvantages

3. What is modulation? Explain in detail. Introduction Digital modulation, Analog modulation Antennas Frequency division Multiplexing Medium Characteristics Spectral efficiency, Power efficiency, Robustness Amplitude Shift Keying Advantages, disadvantages, Applications Frequency Shift Keying Binary FSK Continuous Phase Modulation

Phase Shift Keying Binary PSK Phase lock loop Advanced Frequency Shift Keying Minimum Shift Keying, Gaussian MSK Advanced Phase Shift Keying Quadrature PSK Reference signal

Differential QPSK Quadrature Amplitude Modulation Multi-carrier modulation Advantages

4. Briefly demonstrate the concept of spread spectrum. Direct Sequence Spread Spectrum Chipping Sequence Pseudo-noise Sequence Spreading factor DSSS transmitter & receiver Frequency hopping Spread Spectrum Hopping Sequence Dwell Time Slow & Fast Hopping FHSS transmitter & receiver




5. Describe in detail about cellular systems. Base Station, cell Advantages Higher capacity, less transmission power, local interference only, Robustness Disadvantages Infrastructure needed, Handover needed, Frequency planning Clusters,

sectorized antennas, Borrowing Channel Allocation(BCA), Fixed

Channel Allocation(FCA), Dynamic Channel Allocation(DCA)

6. Describe the mobile services provided by GSM in detail. Bearer Services

Transparent & Non- transparent Bearer Services Tele Services

Telephony

Emergency number Short Message Service Enhanced Message Service Multimedia Message Service

Group 3 fax

Supplementary Services Typical services

7. Explain in detail about the GSM architecture. Radio Subsystem Base Station Subsystem

Base Transceiver Station

Base Station Controller

Mobile Station

Subscriber Identity Module Personal Identity Number, PIN Unblocking Key Network and Switching Subsystem Mobile Services Switching center Home Location register Visitor Location register

Operation Subsystem

Operation and Maintenance center Authentication center Equipment Identity Register

8. Briefly explain about GPRS

GPRS concepts Time slots PTP packet transfer service

QoS profile

Delay GPRS architecture

GSN Mobility management




9. Give a detailed explanation about DECT System architecture

Global network

Local network Home database, visitor database Protocol architecture Physical layer Medium access control layer Data link control layer Network layer

10. Explain briefly about Satellite systems History SPUTNIK SYNCOM

INTELSAT1 Applications Weather forecasting, Radio & TV broadcast satellites, military satellites, satellites for navigation. Global telephone backbone, connections for remote or developing areas, global mobile communication Basics Routing

Fg=Fc Inclination angle, elevation angle Footprint GEO(Geostationary Earth Orbit) Advantages, disadvantages LEO(Low Earth Orbit) Advantages, disadvantages MEO(Medium Earth Orbit) Advantages, disadvantages HEO(Highly Elliptical Orbit) Advantages, disadvantages Localization Home Location register(HLR) Visitor

Location register (VLR) Satellite user

mapping register(SUMR) Handover.

Intra-satellite, inter-satellite, Gateway, Intersystem handover

11. Explain the types of broadcasting in detail. Digital Audio Broadcasting (DAB) Transport mechanisms Main Service Channel

Fast Information Channel

Multi-media object Transfer protocol Header core, Header extension, Body Object repetition, Interleaved objects, segment repetition, Header repetition Digital Video Broadcasting (DVB) Contents of DVB Network Information Table, Service Description table, Event Information table, Time and date table DVB Data Broadcasting Data pipe, Data Streaming,, multiprotocol encapsulation, data carousels, object carousels. DVB for high-speed Internet access




12. Give a detailed description about the physical layer of IEEE 802.11 Frequency hopping Spread Spectrum Functions Synchronization, Start frame delimiter, PLCP_PDU length word, PLCP signaling field, Header error check Direct Sequence Spread Spectrum Synchronization, Start frame delimiter, signal, Service, Length, Header error check Infra red

13. Make a detailed description about MAC management. Synchronization Timing Synchronization function Beacon Beacon transmission in Infrastructure network Ad-hoc network

Power management Sleep & awake states

Power management in Infrastructure network

Traffic indication map

Delivery Traffic indication map PS(power saving) poll

Ad-hoc network Ad-hoc Traffic indication map

Roaming

Steps Scanning

Passive & active scanning Association request

Association response Updation of database

14. Explain briefly about HIPERLAN1 Phases Prioritization

Elimination Yield

Transmission

Quality of Service support and other specialities MSDU Lifetime

Power Conservation Encryption, decryption

15. Give a short description of the Bluetooth architecture Networking Piconet

Scatternet Protocol stack Core specifications, profile specifications Core protocols Link manager protocol, Logical link control & adaptation protocol, service discovery protocol Cable replacement protocol, telephony control protocol specification Host controller interface




16. What are the advantages and disadvantages of WLANs? Explain. Advantages

Flexibility

Planning Design

Robustness Cost

Disadvantages

Quality of

service

Proprietary solutions

Restrictions

Safety and security 17. Briefly explain about the goals, assumptions and requirements of mobile IP.

Quick ‘solutions’ Requirements

Compatibility

Transparency

Scalability and efficiency Security

18. Give a detailed note about tunneling and optimization in mobile IP. Tunneling & Encapsulation IP-in-IP encapsulation

Minimal encapsulation Generic routing encapsulation

Optimization

Triangular routing, binding cache Four additional messages Binding request Binding update

Binding acknowledgement Binding warning

Reverse tunneling Firewalls

Multi-cast

TTL 19. Explain the concept of routing in MANET

Fundamental differences between wired & wireless ad-hoc networks Asymmetric links Redundant links

Interference

Dynamic topology

Problems with ad-hoc routing Need for algorithms with high dynamic topology Information from lower layers essential Centralized approaches will not work Efficient routing capabilities are needed Notion of connection with certain characteristics will not work Flooding




20. Write short notes on DSR and DSDV Dynamic Source Routing (DSR) 2 phases in routing Route discovery Route Maintenance Basic operation Optimization of the basic algorithm Approaches for Route Maintenance Destination Sequence Distance Vector (DSDV) Sequence numbers Damping Routing table

21. Give a detailed explanation about Agent Discovery and registration of mobile IP. Agent advertisement. Agent advertisement message Agent advertisement packet Type #addresses Lifetime Preference Length, bits Agent solicitation Three solicitations: one per second Decrease solicitations exponentially Registration

22. Give a detailed view of traditional TCP. Congestion Control

Dropped packet Retransmission of missing packet Slow Start Congestion window Congestion threshold Exponential growth Fast retransmit/ Fast recovery Implications on mobility Error rates Packet loss

23. Explain indirect TCP in detail. Socket and state migration after handover of a mobile host Advantages No change in TCP protocol Transmission errors on wireless links cannot propagate into the fixed network Different solutions can be tested without jeopardizing the stability of the

internet Uses precise time-outs to guarantee retransmissions as fast as possible Partitioning allows the use of different transport layer protocol

Disadvantages Loss of end-to-end semantics of TCP might cause problems Increased handover latency may be problematic FA must be a trusted entity.




24. Give a detailed description about Mobile TCP. 2 parts Unmodified

TCP Optimized TCP Persistent

mode Bandwidth manager

Advantages

Disadvantages

25. Describe in detail about WAP architecture Bearer services Transport layer Service Access point (T-SAP)

Security layer Security SAP (SEC-SAP) Transaction layer

Transaction SAP (TR-SAP) Session layer

Session-SAP (S-SAP) Application layer

Integration of www and mobile telephony applications Integration of WAP components

IT6601 – MOBILE COMPUTING

Question bank – Detailed Questions UNIT –I 1. Discuss the advantage and disadvantage of cellular system with small cells (06)

2.Briefly explain the Frequency Division Multiplexing (06)

3.Write short notes on DHSS (04)

4.Write short note on FHSS (04)

5.Explain the GSM system architecture with a neat diagram. (16)

6.Describe the security services provided by GSM. (08)

7.Explain the protocol architecture of GSM for signaling. (16)

8.Explain the architecture of GPRS with a neat diagram. (10)

9.What are typical steps for handover on GSM network? (08)

10.Explain the steps involved in the call delivery procedure in GSM network in the following cases:

(i) GSM mobile terminated call (08) (ii) GSM mobile originated call (08)

11. Why are so many different identifiers/addresses needed in GSM?

Give reasons and distinguish between user-related and system related

identifiers. (08)

12. Explain the services provided by GSM? (08) 13. Write short notes on

(i) Mobile management. (08)

(ii) Connection Establishment. (08)




UNIT-II

1.Compare HiperLAN and Blue tooth in terms of ad-hoc capabilities, power saving mode, solving hidden terminal problem, providing reliability fairness problem regarding channel access. (16) 2.Write short notes on wireless PAN? (04)

3.Explain the operation of DFWMAC_DCF with a neat timing diagram.(8)

4. Draw the MAC frame of 802.11 and list the use of the fields. (8)

5.Describe HiperLAN architectural components and their interactions. (16)

6.Explain the architecture of Wi-Fi in detail. (16)

7.Explain the system architecture of IEEE 802. 11 (16)

8.Describe the architecture of WiMAX in detail. (16)

9.Compare and Contrast Wi-Fi and WiMax. (06)

10. Briefly explain about BRAN. (04)

11. Explain in detail ablout Wireless ATM. (10)

12. Explain the information bases and networking of adhoc HIPERLAN. (8) 13. Discuss MAC layer Bluetooth system (08)

UNIT – III

1.Show the steps required for a handover from one FA to another FA including layer-2 and layer-3. Assume 802.11 as layer-2. (08)

2. Name the ineffiencies of Mobile IP regarding data forwarding from CN to

MN. W hat are the optimizations possible? (08)

3. What are the differences between wired networks and ad-hoc networks

related to routing? (06)

4. What is the need for DHCP? With a state chart explain the operation of DHCP? (10)

5.List the entities involved in mobile IP and describe the process of data transfer from a mobile node to a fixed node and vice versa. (08)

6. Why is conventional routing in wired networks not suitable for wireless networks? Substantiate your answers with suitable examples. (08)

7. Discuss DSDV routing in detail. (16)

8. Describe how the multicast routing is done in ad-hoc networks. (08) 9. Explain how tunneling works in general and especially for mobile IP using IP-in-IP,

MINIMAL,and generic routing encapsulation, respectively. Discuss the advantages and disadvantages of these three methods.(16)

10. How does dynamic source routing handle routing? What is the motivation between dynamic source routing compared to other routing algorithms from fixed networks? (16)

11. Briefly explain about CGSR. (06) 12. Compare and Contrast about Proactive and Reactive routing protocol(4)




UNIT IV

1. Explain the mechanisms of TCP that influence the efficiency in mobile

environment. (08)

2. Explain the operation of Mobile TCP. (08) 3. Compare and Contrast Traditional and Mobile TCP. (04)

4. Why has a scripting language been added to WML? How can this language help saving bandwidth and reducing delay? (08)

5.Which WTP class reflects the typical web access best? How is unnecessary overhead avoided when using

WSP on top of this class of web browsing? (10)

6.State the requirements of WAP. Explain its architectural components. (16)

7.Explain WML and WML scripts with an example. (16)

8.What is WTP? Discuss about its classes. (08)

9.Explain the architecture of WTA. (08)

UNIT V

1.What are the design and implementation issues in device connectivity aspect of pervasive computing?

Explain (08)

2.Explain the operating system issues related to miniature devices.(08)

3.Explain the various soft surface and semi-soft-surface-based display system and technologies. (16)

4.Describe the various hardware components involved in pervasive computing devices. (08)

5.Explain how a pervasive web application can be secured using an ‘Authentication Proxy’. (08)

6.What are the applications of pervasive computing? Discuss any two of them. (08)

7.Explain how pervasive web applications can be accessed via WAP. (10)

Documents

IT6601 Mobile Computing 2 mark question and answers · SYED AMMAL ENGINEERING COLLEGE Dr.E.M.Abdullah Campus, Ramanathapuram - 623502 Department of Information Technology IT6601 Mobile